UNIST and Yonsei University Develop Eco-Friendly Solvent-Based Direct Patterning Process for Two-Dimensional Semiconductors

Prevents Damage to Semiconductor Materials and Reduces Process Toxicity
Demonstration of Semiconductor Device Fabrication
Expected to Aid in the Development of Low-Power, High-Speed Computing Chips Based on Two-Dimensional Semiconductor Materials
Published in Adv. Mater.

A new technology has been developed that allows circuits of two-dimensional semiconductor materials to be drawn directly onto a substrate without complex processes.

This technology involves patterning by mixing semiconductor materials and a crosslinker in an eco-friendly solvent. It replaces toxic organic solvents and prevents material damage during processing, making it a promising process technology that could accelerate the commercialization of next-generation, high-density, low-power semiconductor chips.

On September 18, Professor Bongsoo Kim's team in the Department of Chemistry at Ulsan National Institute of Science and Technology (UNIST) announced that, through joint research with Professors Jungho Cho and Joonghoon Kang at Yonsei University, they have developed a technology for directly patterning two-dimensional semiconductor materials such as molybdenum disulfide and a crosslinker onto a substrate using an eco-friendly solvent.

Research team: Professor Bongsoo Kim of Ulsan National Institute of Science and Technology (UNIST), Professor Jungho Cho and Professor Joonghoon Kang of Yonsei University, Researcher Wanho Cho (first author) and Researcher Yuchan Heo of UNIST. Provided by UNIST

Two-dimensional semiconductor materials are layered materials similar to paper. While these materials are expected to increase the integration density of semiconductor chips and reduce power consumption, it has been difficult to process sensitive two-dimensional materials into circuit patterns without damage using conventional semiconductor processes.

The technology developed by the research team enables direct drawing of circuits made from two-dimensional semiconductor materials without high-temperature or chemical treatment processes such as deposition or etching. By mixing two-dimensional nanomaterials and a crosslinker in an eco-friendly alcoholic solvent, the circuit is drawn and then exposed to ultraviolet light. When the crosslinker is exposed to ultraviolet light, it hardens and fixes the nanomaterial in the shape of a circuit. Any crosslinker outside the circuit can be easily removed by washing with water.

The key to developing this process technology was finding an eco-friendly solvent that could uniformly disperse two-dimensional materials and a crosslinker that dissolves well in that solvent. Through quantitative analysis, the research team selected isopropanol as the solvent and modified the chemical structure of a conventional azide-based crosslinker so that it would dissolve well in isopropanol. Azide-based crosslinkers do not typically dissolve well in alcoholic solvents.

The molybdenum disulfide transistor produced using the new process recorded an electron mobility of 20.2 cm²/V·s, a threshold voltage of 2.0 V, and an on/off current ratio of 2.7×10?. An array of 49 transistors also operated stably for more than 60 days without performance variation between individual transistors.

In addition, the team succeeded in patterning both p-type and n-type two-dimensional materials simultaneously on a single substrate, enabling the fabrication of NOT, NAND, and NOR logic circuits as well as SRAM. This achievement demonstrates the commercial viability of the process technology.

Professor Bongsoo Kim stated, "This research proves that crosslinker-based ultraviolet patterning technology, which is used in EL-QD display manufacturing, can be extended to two-dimensional semiconductor materials," adding, "It will contribute to the development of next-generation low-power, high-speed computing semiconductor chips based on two-dimensional semiconductor materials."

Direct patterning process of eco-friendly solvent-based two-dimensional semiconductor materials and semiconductor devices fabricated by the process.

This research was conducted with Wanho Cho of UNIST, Incheol Kwak and Sejin Kim of Yonsei University as first authors. The results have been published online in the international journal Advanced Materials and are awaiting formal publication.

The research was supported by the Samsung Future Technology Development Program.

This content was produced with the assistance of AI translation services.